The Enemy Of My Enemy Is My Friend
by Insanity-is-Freedom
Summary: Peter was weak and pathetic and a rat. Regulus was a pureblood, handsome and powerful. He was also a dog and dogs just like rats have a certain hatred for cats. And sometimes a Cat is all that is needed for a Rat and a Dog to become friends. Can be seen as RBPP - ONESHOT


**I just discovered today that I liked Peter and then I got a flash of inspiration and wrote this. It's mostly friendship but I suppose if you wanted to be it could be considered slash, or pre-slash more like.**

 **Don't hesitate to leave some reviews to tell me what you think of it!**

 **Disclaimer:** **I don't own Harry Potter. If I did I wouldn't be writing fanfiction because all my ideas would be canon.**

* * *

If banality had been a person, it would be Peter Pettigrew. He didn't think you could get any more common than this. Short locks of a dirty blonde and uninspiring blue eyes set in a wan face. He didn't need to look in a mirror to know what everyone saw. A skinny figure, eyes always looking down, jittery smile and nervous gestures. He disgusted himself. It made him wonder how he ever came to befriend and become one of the Marauders. He didn't have any of James' charisma or Sirius' good looks. He couldn't even boast intelligence like Remus. He was just dull uninteresting Peter. Gryffindor's coward. The Marauders' sidekick. He had nothing, absolutely nothing going in his favour. Even his inner animal, which had been revealed when he had been developing his Animagus form along with James and Sirius, even that was pathetic. A rat. That just showed you didn't it? How pathetic he was. How utterly miserable a person he was. Inside and out.

So really it was no wonder that he would fail at something as stupid as an essay. He could never get anything right. It wasn't surprising that people got annoyed. Like McGonagall. She was nice really. She was a good teacher, albeit a strict one. She was her Head of House and she had always been patient with him. Until he had failed once too many. It was his own fault for being so pathetic. If he had been just a little bit smarter, a little less pathetic, he could have given her a proper essay. And she wouldn't have given him detention to rewrite it. That's how bad it had been.

It was all his fault, he told himself as he stopped in front of McGonagall's office. He looked glumly at the bronze head of a lion holding a ring in his mouth before grabbing it resolutely and knocking twice on the door with it.

"Enter." called the woman's voice from inside.

He pushed the door open and went in, head bent down. He wished he could look up into people's eyes with the same look of unwavering confidence as James, but he was simply too ashamed of himself to do that. He was too weak, too small, too pathetic.

"Good evening Mr Pettigrew. I trust you brought parchment, ink and a quill?" she paused just long enough to see him nod. "In that case you may sit next to Mr Black and get started."

He whipped his head up at the mention of the familiar name, too surprised to remember to be afraid of meeting someone's eye. He hadn't heard of Sirius getting detention. If he had, surely they would have walked there together. He felt a small twinge of hurt at the thought that maybe Sirius didn't really think of him as a friend. Which wouldn't be surprising really. But the thought faded away as soon as his eyes landed on his fellow student.

It wasn't Sirius. The boy had the same longish dark hair and the same silver grey eyes, but his features were more childish. Not to mention the tie around his neck was green and silver. Slytherin colours. Sirius would rather die than wear something like that. No, this wasn't Sirius. Which only left one possibility: his younger brother, Regulus Black.

He'd been staring, his mouth ajar. And the dark haired Slytherin had been staring right back. Though he did so with much more distinction, his features schooled into polite curiousness. As soon as Peter met the other boy's eyes, he dropped his gaze, feeling his cheeks burn with shame.

Quick and silent, like the rat scuttling in the dark whom he knew intimately, he made his way to the table and plopped himself in his chair. He took out his things hurriedly, burying himself in work so as to avoid any kind of embarrassing interaction with the younger Black. Thankfully, the boy's interest seemed to have been only a façade and he had gladly gone back to his own work, leaving Peter to try and focus his mind on cross-species Transfiguration.

His inability to concentrate was all the more frustrating for Peter because he should have known the subject. As an illegal Animagus himself, he had studied cross-species transfiguration extensively. Certainly he had been largely helped by the Marauders, but he had done the reading himself. He knew he had knowledge, it just wouldn't come out right when he was trying to write about it. Forget about writing, he couldn't even concentrate properly! His eyes kept shifting to the side to where Black was diligently writing lines.

This was perhaps the first time, he had found himself in close contact with the boy. Of course he had seen him before. From afar. Mostly the boy had been in company of his brother and Peter had happened to give them a longing glance. He was an only child and had always envied siblings. The glance never lasted long though. He was always quick to drop his gaze to the ground, like the coward, the _rat_ he was.

He didn't know if it was nervousness, his jealousy for siblings or curiosity that pushed his gaze to stray from his work to look at the boy beside him, but he was starting to irritate himself. The more time passed, the more his own behaviour unnerved him. If he didn't get on with his work, McGonagall would surely make a scathing remark and perhaps even give him detention for the rest of the week. Worse, Black might notice. He could already feel the mortification of being caught sneaking glances.

No, he told himself. He had to concentrate. He fixed his blue eyes on the blank parchment in front of him, willing it to stay there.

He had just placed the tip of his quill on the parchment, when he felt a hand brush against his shoulder.

A squeak escaped his lips, as he positively jumped in surprise. His jerking hand knocked into the ink pot which fell over, crashing on the floor.

Peter froze, his face shocked into a mask of horror as he stared trembling at the wreckage.

"Mr Pettigrew." started McGonagall between clenched teeth.

Peter hunched on himself, trying to make his already small figure as minuscule as he could under the fiery gaze of the Transfiguration teacher, his ratty heart beating rapidly as he awaited the inevitable scolding.

"It was my fault Professor." intervened Black smoothly. "I startled him."

Peter peeked at the other boy out of the corner of his eye. He certainly hadn't expected the boy to defend him. Rather, he had expected him to make fun of him as anyone else, even his so-called friends, would have. It was all deserved after all. But no, here he was, defending him, as if he cared about Peter. As if Peter was worth it.

"Well, I would ask that you would refrain from doing so from now on." said McGonagall, sounding almost as taken aback as Peter felt.

She gave a jerky wave of her wand and the broken ink bottle mended itself, the ink returning to it obediently.

"Now get back to your work."

The detention resumed silently, Peter finally managing to concentrate on his essay and Black paying him no more attention.

When the teacher dismissed them later in the evening, Peter gathered his courage and trembling from head to toe, he took a deep breath.

"Thanks for helping me." he blurted out.

He lifted his eyes, knowing it would be proper to look at the other, only to find an empty corridor staring back at him. Black had already left.

His shoulder sagged, his head dropped and he started trudging back to the common room. He couldn't even say 'thank you' properly. Of course, he couldn't. He was Peter Pettigrew. Idiot Extraordinaire. He couldn't do anything right. He was so pathetic.

* * *

He had been bored. McGonagall had him writing lines, and Merlin knew there was no excitement to be found in it. So when that wimpy Pettigrew had come in, he had welcomed the distraction. A short distraction certainly, but long enough for him to take a break from the dull repetition of lines. Just enough for him to clear his head before going back to work. Or so he had thought. In truth, concentrating on lines after being distracted had been a bit of a challenge.

He blamed the boy's eyes. The boy had jerked his head up abruptly, eyes flying to his, a shock of blue that had made his heart skip a beat. They were wide, fearful and _intense_. If magic could be seen with the naked eye, he imagined it would have the same kind of intensity. But the illusion hadn't lasted. Pettigrew's gaze had dropped as suddenly as it risen, and the boy had scuttled to his seat. And that was the end of it. At least it should have been.

As it was, Regulus found himself peaking at the boy as he took out his parchment, glancing inside his surprisingly well-ordered bag. He hadn't thought Pettigrew was the type of person to neatly arrange books in his bag by size, but it evidence to the contrary was in clear sight. Effortlessly his eyes read the title of one of them. _How to find your inner animal_. It shouldn't have piqued his interest, but it did.

Then it was the eyes again, constantly shifting to himself. He showed no sign of noticing but he saw the glances. They unnerved him. They amused him. He wished they would stop and somewhat hoped they wouldn't. He glanced to the side as well a few times, noticing the tension in the other's shoulders, the way his jaw was clenched as he tried his hardest to keep his gaze on the parchment in front of him.

He didn't know what brought about the sudden impulse to touch him. He managed to convince himself it was about the book. Of course it was the book. Couldn't be anything else. But he forgot all about it upon witnessing Pettigrew's reaction. Who squeaked? Pettigrew obviously. Regulus could have laughed if he wasn't too busy staring at the falling inkpot and after it crashed the widening pool of dark blue liquid. When that cat of a woman hissed at the Gryffindor, his voice rose without permission, taking the blame as naturally as if he did it every day. He had time to reflect on it afterwards. An hour and a half to be precise. His conclusion was that he had been possessed. It wouldn't happen again.

When the woman released them, he gathered his things swiftly, left his lines on her desk and left. He was gone before the office door shut behind Pettigrew.

He would have happily forgot about all of it. In fact, he did. For a few days at least. But it all came back rushing to him one evening as he caught sight of the ratty figure sitting alone in an obscure corner of the library, reading a book Regulus recognized. He'd stopped short and analysed the situation with a calm that surprised him. He was alone, his friends having preferred to retreat to the Slytherin common room. There was no one around. He had nothing better to do. And he was somewhat intrigued.

He stepped forward.

"What are you reading?" he asked the older boy.

The boy jumped in surprise, but this time he didn't squeak. Regulus knew what he was reading of course. _How to find your inner animal_. He had recognized it.

The eyes of a shocking blue stared at him and a snide voice in his mind commented that maybe it wasn't the book he was interested in. He told it to shut up.

"Do you mind if I sit with you?"

The boy hadn't answered and it didn't surprise him. Pettigrew was a coward. But it didn't matter. He didn't even know for what reason he had spoken to him.

"No." murmured Pettigrew weakly.

Regulus gave him a smile for his efforts. Nothing genuine, but Pettigrew didn't seem to realize it wasn't as he made a pathetic attempt at a smile himself. He was too scared for it to work well.

Regulus sat. And wondered what to do. His Charms homework would be a good start he supposed.

* * *

Why would Sirius' brother talk to him, he had no idea. It seemed surreal that someone, anyone, would pay any attention to poor pathetic Peter, let alone Black. A pureblood. A Slytherin. His paranoid mind immediately started feeding him various scenarios of pranking, humiliation and pain. But somehow none seemed to coincide with the friendly tone and the smile. He attempted to return it. He didn't think he managed it very well. He never could do anything well, he thought dejectedly as the dark haired boy took out books and parchment from his bag.

He tried to go back to his reading, but he knew the pages by heart having read it many times before. He liked it well enough, but he couldn't manage the interest just then. The way his eyes drifted to the boy's face reminded him of detention with McGonagall. But that time, his gaze had only gone as far as the boy's hands and arms, never higher. But now, when he glanced up, it was Black's face he saw.

He was handsome. Much like his brother. But his coolness gave him a more refined sort of beauty. It wasn't as obvious without Sirius' outgoing personality but it had a distinction Sirius could never achieve. But he did have the same doggish expression that Sirius had and that made girls cue about how adorable he was. He gulped. Clearly, Black was way out his league. He was the type of person Peter could normally not ever dream of approaching. Let alone befriending. He shook his head. What was he thinking? It was ridiculous of him to think of befriending Regulus. Black.

He glanced up again. He couldn't help himself. Black was looking at his parchment thoughtfully, eyebrows knitted in a frown. Curiosity got the better of him and the blue gaze descended to the parchment. Looking back up at the boy's slightly confused expression, it occurred to Peter that he might need help. He gulped. He would never dare. But he had already failed to say his thanks. It was his chance.

He took a deep breath, willing his hands to stop trembling.

"C-Can I help you?" Black looked up midsentence, causing Peter to end in a squeak.

He looked a bit surprised to be spoken to. He was staring straight at Peter and the Gryffindor dropped his gaze.

"Sure." said Black and the blue gaze looked up again to find him smiling. "Here it's this."

As he bent over the Charms questions, Peter found it difficult to remember the pessimist scenarios his mind had conjured a few minutes before. Regulus had a strange effect on him. It was almost as if he thought Peter was worth it. Which he clearly wasn't.

He wasn't but he wanted to be, so when a few days later he happened on a group of older Slytherins surrendering Regulus and sneering down at him, he didn't hesitate to grab his wand with shaking hands.

" _Fumos."_ he murmured with a wave of his wand.

The smoke appeared covering the scene and hiding him from view. It also hid Regulus, but Peter had memorized his position so it only took a moment for him to grab his sleeve and run away, dragging the boy with him. He pulled him into corridors, taking a sharp turn and leading him into a hidden passage. There was some good in being a rat: you knew all the hidden corners and escape routes there was to know. And it served him well as he pushed Regulus against the wall, holding him with both trembling hands, his own body pressed against the other as they held their breath. Hurried footsteps and angered voices could be heard passing by, but the Slytherins passed them by without seeing them.

When the voices were gone and his tension had decreased, Peter noticed the closeness and jumped back in a hurry. He peered at Regulus' expression. There was that smile again. Friendly and intrigued.

"Thanks." said the boy. "You were a great help back there."

Peter's ratty heart swelled. Regulus had given him something no one else had ever given him. Something he had never thought he deserved. Something he had never even dreamt of receiving. Until now.

* * *

After that fateful day when Peter had saved him from a bunch of bullies, they had become friends. It was as surprising to him as it had been to Peter. Who would have thought the heir of the Most Ancient and Noble House of Black would befriend the ratty coward of Gryffindor? But there they were, huddled side by side in a dark corner of the library or in an abandoned classroom talking about nothing and everything. Regulus had revealed many of his hidden sides to the boy and in turn he had learnt many things about Peter that no one had ever suspected.

The first he noticed was that if Peter was easily frightened, he wasn't a coward. He was small and weak, but he had grabbed him that day, and taken him away from his bullies. It hadn't been a straightforward fight, but it had taken courage. Regulus could see why Peter had been sorted in Gryffindor.

Another thing he noticed early on was that Peter was exceedingly good at Charms. He understood them quickly and mastered them in no time. The only problem was his excessive lack of confidence.

Peter thought himself ugly and pathetic, he couldn't see the appeal his eyes had, or the talent he had for Charms. He couldn't see the courage in himself that had made him grab Regulus. He couldn't see the loyalty that made him stick to their friendship even when Regulus told him he had joined Voldermort. He couldn't see it. But Regulus could. Him and no one else. For all their popularity and talent, Sirius and James Potter didn't know the beauty of the little rat's heart. But Regulus knew.

They made a strange pair, he sometimes thought. A dog and a rat. He knew his inner animal was a dog, because he and Peter had done the experiment following the instructions in the book that may or may not have started it all. A strange pair. He didn't mind.

Even after they left Hogwarts and Regulus was a faithful Death Eater, they continued meeting.

He didn't know why he said it. He concluded he had been possessed. It had happened again. He'd told Peter he loved him. He wasn't sure what he meant by it. Or what he expected Peter to do. But he should have expected that his fearful rat would run away. He should have but he didn't and Peter did.

He was dying now. He had tried to make a difference. There had been a thought in his mind of going back to the Light. Where Peter was. Or was it a sense of justice? Was it his eyes? He was dying. And a tear was falling down his cheek. He was a bit puzzled. He wasn't crying. But then he saw the shock of blue.

"Regulus."

Broken voice, broken heart. The tears were falling from Peter's cheek and onto his.

"Regulus, please."

The voice choked. He liked it when Peter called his name.

"Regulus, I love you."

It was the last thing he heard. He wasn't sure what Peter meant by it. But he sure was happy all the same.

* * *

Peter had always been pathetic. Until Regulus had told him otherwise. Until, Regulus had given something no one else had given him. Something called Recognition.

And now he wept for the loss of the dog who had saved him from a cat. And as he raised his eyes towards the snake in the sky, he made up his mind. The snake would replace the cat as his enemy. Because after all, if the enemy of his enemy was his friend, the enemy of his friend might as well be his own enemy.


End file.
